import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class Client {
    private DatagramSocket socket = null;

    private String serverIp = "";

    private int serverPort = 0;

    public Client(String ip , int port ) throws SocketException {
        //不能手动指定端口
        socket = new DatagramSocket();
        //记录对端的ip 和 端口
        serverIp = ip;
        serverPort = port;
    }

    public void start() throws IOException {
        System.out.println("客户端启动");
        Scanner scanner = new Scanner(System.in);
        while(true) {
            //1.从控制台读取数据，作为请求
            System.out.println("->");
            String request  = scanner.next();
            //2.把请求构造成一个 DatagramPacket 对象，发送给服务器
            DatagramPacket requestPacket = new DatagramPacket(request.getBytes() , request.getBytes().length,
                    InetAddress.getByName(serverIp) , serverPort);
            socket.send(requestPacket);
            //3.尝试读取服务器返回的响应
            DatagramPacket responsePacket = new DatagramPacket(new byte[4096] , 4096);
            socket.receive(responsePacket);
            //4.把响应转换为字符串，并且显示出来
            String response = new String(responsePacket.getData(),0 ,  responsePacket.getLength());
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
        Client client = new Client("127.0.0.1" , 9090);
        client.start();
    }
}
